Process for the preparation of 3,4,6-trifluorophthalic acid and the anhydride thereof

US5200556A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Theodor Papenfuhs · Frankfurt, DE
• Ralf Pfirmann · Griesheim, DE

Key dates

• Filing date: May 21, 1992
• Grant date: Apr 6, 1993
• Expiry date: May 21, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/567
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for the preparation of 3,4,6-tetrafluorophthalic acid of the formula (1) ##STR1## or the anhydride thereof in good yields and in an advantageous manner, by dehalogenating tetrafluorophthalic anhydride of the formula (2) ##STR2## or tetrafluorophthalic acid in aqueous-alkaline medium using zinc at temperatures of approximately 20.degree. C. to approximately 160.degree. C. and, if appropriate, converting the resulting 3,4,6-trifluorophthalic acid into the anhydride in a known manner by dehydrating it.